The results of extensive studies of concepts for
structurally-connected and formation-flying interferometer
for the TPF mission will be presented. Strawman concepts
were developed to meet the science requirements of detecting
planets around 30 stars for the structurally-connected
concept and 150 planets for the formation-flying concept.
Trade results show that the dual-chopped Bracewell
configuration best meets the science objectives when
compared to OASES and degenerate Angel Cross nulling
architectures. The trades considered launch packaging
constraints and beam combiner complexity. Capabilities for
detection of spectral biomarkers will also be presented.